But nothing beats Delrin non static mat from Jim Howard: info@appliedfidelity.com
It is adhered with pliable adhesive forming an airtight seal under the mat and then screwd down.
with a groove for 10" Lps.
It enhances the tank-like look of the 1200.

Upping the weight to 1lb made a nice increase on bass definition.

brass pipe cap vs aux weight from KAB

The weight of
the 103 was so heavy with the Sumiko headshell and ebony or
Panzerholtz that I needed to add the brass to the counterweight.

SCOTTRT suggestion: heat shrink. 5/8 to 3/4 inch size,
which will slip easily over the headshell collar. This added a better
sense of a tactile, snappy.Swapped in a MG5 tonearm w/ oxygen free copper and used Canare leads /w Eichmann bullets. Nice improvement. Not sure if it just the
Canare or the addition of the tonearm wire but it is clean, clear, open,
smooth, etc. There was a thickness to the sound which is now gone
entirely.
Resource: http://www.djresource.eu/Topics/story/109/SL-1200-1210-Opening-the-Hood/

Rega RB-250 on deck

Two 3 gram weights at headshell along with the added Panzerholtz weight*
makes it over 16 grams effective mass.Re-wired the arm /w Cardas from nice rhodium plated clips to Eichmann RCAs
Heatshirink on the finger lift.

* Original 103 = 1.6g.
Panzerholz 103 = 5.4g.

Went back to the MG5 arm. It is livelier, more detailed, that VTA thing, swap carts easier, better.
The RB250 was kind of dull.

Hooked the arm up with KABs RCA jack.
Nice and secure. I can swap cables. More fun.